diff --git a/ulib/debian b/ulib/debian
index de66123..1746650 100644
--- a/ulib/debian
+++ b/ulib/debian
@@ -114,11 +114,18 @@ END {
 
 __DEBIAN_NETWORK_DEVEL_SHOW_MODIFS=
 
+function __network_backup() {
+    local file="$1"
+    local backup="$file.orig$(date +%Y%m%d)"
+    [ -f "$backup" ] || cat "$file" >"$backup" 2>/dev/null
+}
+
 function __network_hostname() {
     local hostname="${1%%.*}"
     if [ -n "$__DEBIAN_NETWORK_DEVEL_SHOW_MODIFS" ]; then
         uecho "Setting /etc/hostname to $hostname"
     else
+        __network_backup /etc/hostname
         echo "$hostname" >/etc/hostname
     fi
 }
@@ -128,6 +135,7 @@ function __network_mailname() {
     if [ -n "$__DEBIAN_NETWORK_DEVEL_SHOW_MODIFS" ]; then
         uecho "Setting /etc/mailname to $host"
     else
+        __network_backup /etc/mailname
         echo "$host" >/etc/mailname
     fi
 }
@@ -146,9 +154,11 @@ function __network_fix_exim4() {
             uecho "/etc/exim4/update-exim4.conf.conf: pas de modifications"
         fi
     elif testdiff "$tmpfile" /etc/exim4/update-exim4.conf.conf; then
+        __network_backup /etc/exim4/update-exim4.conf.conf
         cat "$tmpfile" >/etc/exim4/update-exim4.conf.conf
         update-exim4.conf
     fi
+    ac_clean "$tmpfile"
 }
 
 function __network_hosts() {
@@ -171,11 +181,37 @@ $ip$TAB$host $hostname" "$tmpfile"
             uecho "/etc/hosts: pas de modifications"
         fi
     elif testdiff "$tmpfile" /etc/hosts; then
+        __network_backup /etc/hosts
         cat "$tmpfile" >/etc/hosts
     fi
     ac_clean "$tmpfile"
 }
 
+function __network_reset_interfaces() {
+    local tmpfile; ac_set_tmpfile tmpfile
+
+    echo >"$tmpfile" "\
+# This file describes the network interfaces available on your system
+# and how to activate them. For more information, see interfaces(5).
+
+# The loopback network interface
+auto lo
+iface lo inet loopback
+"
+    if [ -n "$__DEBIAN_NETWORK_DEVEL_SHOW_MODIFS" ]; then
+        if testdiff "$tmpfile" /etc/network/interfaces; then
+            uecho "Setting /etc/network/interfaces to:"
+            cat "$tmpfile" | sed 's/^/    /g' 1>&2
+        else
+            uecho "/etc/network/interfaces: pas de modifications"
+        fi
+    elif testdiff "$tmpfile" /etc/network/interfaces; then
+        __network_backup /etc/network/interfaces
+        cat "$tmpfile" >/etc/network/interfaces
+    fi
+    ac_clean "$tmpfile"
+}
+
 function __network_parse_confip() {
     # confip --> iface [ipspecs@] [ipspecs]
     local __npc_tmp
@@ -265,6 +301,8 @@ function __network_resolve_mainiface() {
 }
 
 function __network_set_mainip() {
+    # XXX modifier pour en faire set_confips, qui initialise confips en fonction
+    # des adresses actuelles, principale et supplémentaire
     eval "$(ip addr show dev "$1" | awk "BEGIN {
   mainipvar = \"${2:-mainip}\"
   netmaskvar = \"${3:-netmask}\"
@@ -308,7 +346,9 @@ function __network_update_bridge() {
     # bridge, bridge en auto, adresse ip principale statique ou en dhcp,
     # adresses ip supplémentaires), puis si nécessaire, supprimer l'ancienne
     # configuration et créer la nouvelle.
-    awkrun -f iface="$1" ipspecs="${2:-ipspecs}[@]" ifaces="${3:-ifaces}[@]" '
+    local inf="$1"; shift
+    local outf="$1"; shift
+    awkrun <"$inf" >"$outf" -f iface="$1" ipspecs[@]="${2:-ipspecs}" ifaces[@]="${3:-ifaces}" '
 { print }
 '
 }
@@ -318,9 +358,106 @@ function __network_update_iface() {
     # adresse ip principale statique ou en dhcp, adresses ip supplémentaires),
     # puis si nécessaire, supprimer l'ancienne configuration et créer la
     # nouvelle.
-    awkrun -f iface="$1" ipspecs[@] '
+    local inf="$1"; shift
+    local outf="$1"; shift
+    local IPSPECS_SCRIPT='
+  method = "dhcp"
+  ips_count = ipspecs_count
+  array_new(ips)
+  array_new(masks)
+  array_new(gateways)
+  array_new(have_ups)
+  array_new(have_downs)
+  for (i = 1; i <= ips_count; i++) {
+    if (match(ipspecs[i], "^(.*)(/(.*))?(\\+(.*))?$", vs) != 0) {
+      ip = vs[1]
+      mask = vs[3]
+      gateway = vs[5]
+    } else {
+      ip = ""
+      mask = ""
+      gateway = ""
+    }
+    if (i == 1) {
+      if (ip == "dhcp") method = "dhcp"
+      else method = "static"
+    }
+    if (mask == "") mask = "255.255.255.0"
+    ips[i] = ip
+    #masks[i] = mask
+    #gateways[i] = gateway
+    have_ups[i] = 0
+    have_downs[i] = 0
+  }
+'
+    awkrun <"$inf" -f iface="$1" ipspecs[@]="${2:-ipspecs}" '
+BEGIN {
+  have_hotplug = 0
+  have_auto = 0
+  have_iface = 0
+  have_method = 0 # static ou dhcp
+  in_iface = 0
+  have_mainip = 0
+'"$IPSPECS_SCRIPT"'
+}
+function indexof_ip(ip,            i) {
+  for (i = 1; i = ips_count; i++) {
+    if (ips[i] == ip) {
+      return i
+    }
+  }
+  return 0
+}
+
+($0 " ") ~ ("^allow-hotplug.* " iface " ") { have_hotplug = 1; next }
+($0 " ") ~ ("^(allow-)?auto.* " iface " ") { have_auto = 1; next }
+$0 ~ ("^iface " iface " inet ") {
+  have_iface = 1
+  if (($0 " ") ~ (" " method " ")) have_method = 1
+  in_iface = 1
+  next
+}
+$0 ~ ("^iface ") { in_inface = 0; next; }
+in_iface && $0 ~ "^[ ]*address " mainip { have_mainip = 1 }
+in_iface && $0 ~ "^[ ]*up (/sbin/)?ip addr add " {
+  if (match($0, "ip addr add (.*)/.* dev " iface, vs) != 0) {
+    i = indexof_ip(vs[1])
+    if (i != 0) have_ups[i] = 1
+  }
+  next
+}
+in_iface && $0 ~ "^[ ]*down (/sbin/)?ip addr del " {
+  if (match($0, "ip addr del (.*)/.* dev " iface, vs) != 0) {
+    i = indexof_ip(vs[1])
+    if (i != 0) have_downs[i] = 1
+  }
+  next
+}
+
+END {
+  check_hotplug = !have_hotplug
+  check_auto = have_auto
+  check_iface = have_iface && have_method && have_mainip
+  check_supplips = 1
+  for (i = 1; i <= ipspecs_count; i++) {
+    if (!have_ups[i] || !have_downs[i]) {
+      check_supplips = 0
+      break
+    }
+  }
+
+  if (!check_hotplug || !check_auto || !check_iface || !check_supplips) {
+    exit 1 # il faut refaire la configuration
+  }
+  exit 0 # tout est ok
+}
+' && return 1
+
+    # il faut refaire la configuration
+    awkrun <"$inf" >"$outf" -f iface="$1" ipspecs[@]="${2:-ipspecs}" '
 { print }
 '
+    return 0
 }
 
 function network_config() {
@@ -430,8 +567,9 @@ function network_config() {
                 fi
             done
 
-            __network_update_bridge "$br" ipspecs ifaces <"$interfaces" >"$workfile"
-            cat "$workfile" >"$interfaces"
+            if __network_update_bridge "$interfaces" "$workfile" "$br" ipspecs ifaces; then
+                cat "$workfile" >"$interfaces"
+            fi
         done
 
         # configurer chaque interface classique
@@ -443,8 +581,9 @@ function network_config() {
                 __network_parse_ipspec "${ipspecs[0]}" mainip mask gateway
             fi
 
-            __network_update_iface "$iface" ipspecs <"$interfaces" >"$workfile"
-            cat "$workfile" >"$interfaces"
+            if __network_update_iface "$interfaces" "$workfile" "$iface" ipspecs; then
+                cat "$workfile" >"$interfaces"
+            fi
         done
 
         # Fin de traitement
@@ -456,6 +595,7 @@ function network_config() {
                 uecho "/etc/network/interfaces: pas de modifications"
             fi
         elif testdiff "$interfaces" /etc/network/interfaces; then
+            __network_backup /etc/network/interfaces
             cat "$interfaces" >/etc/network/interfaces
         fi
         ac_clean "$interfaces" "$workfile"